import sys

from PySide6.QtCore import QSize, Qt
from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton


#Subclass QMainWindow to customize your application's main window 
class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("My App")
        button = QPushButton("Press Me")

        self.setFixedSize(QSize(400, 300))
        self.setCentralWidget(button)

app = QApplication(sys.argv)
window = MainWindow()
window.show()

app.exec()

